The prime minister was accused of “hiding behind the DUP” [Democratic Unionist Party] by refusing to act on the issue – despite “overwhelming” public support in the province.
But Ms May insisted it was a “devolved matter”, to be dealt with “soon” at Stormont – despite the 15-month failure to restore the executive and assembly there.
The controversy was raised in the Commons because a backbench Bill to introduce same-sex marriage has been brought forward jointly by a Labour MP and a Tory peer.
Ged Killen, a Labour MP, told the prime minister: “LGBT [lesbian, gay, bisexual and transgender] rights in Northern Ireland are in limbo.
“The assembly has already voted for equal marriage and public support for it is overwhelming.
“Will the prime minister stop hiding behind the DUP and will she take the opportunity to put her support on record for the Bill being brought forward?”
But Ms May insisted legislation passed by the last Labour government meant the issue of same-sex marriage was for Belfast to decide.
“This is an issue that we have taken up, it is an issue we have championed,” she insisted.
And she added: “We hope that there will be a Northern Ireland executive in place soon that will be able to address these issues.”
The stance appears to sit uneasily with a recent written parliamentary answer, which said same-sex marriage was a devolved matter, but added: “The power of the Westminster Parliament to legislate remains unaffected.
“If this issue were to be raised in Westminster, the Government’s policy is to allow a free vote on matters of conscience such as equal marriage,” the Northern Ireland Office stated.
In November 2015, the Stormont Assembly voted in favour of equal marriage – but the measure was blocked by the DUP using a “Petition of Concern”, on the grounds it lacked sufficient cross-community support.
The DUP is propping up Ms May in Downing Street, following the lost Tory majority last year, providing support in key votes in return for £1.2bn for Northern Ireland.
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